Stiff panels are frequently used in structures, such as, for example, the primary structures of aircraft. Composite materials are more and more widely used in particular, because they allow the mass of such structures to be reduced.
A stiff panel 1 is made up of a skin 2 and stiffeners 3. Often, as in the example of FIG. 1, the stiffener comprises a free surface 311 on the side of the stiffener opposite the panel.
When the stiffener is made of composite material, this free surface is particularly vulnerable to shocks.
Thus, during manufacturing operations as well as during handling of such panels, the simple dropping of a tool can lead to damage of a stiffener, for example, producing delaminations that affect the structural quality of the stiff panel.
The consequences can be very costly. In extreme cases, if the stiffener cannot be repaired, it is necessary to replace the panel.
Using stiffeners with reduced shock sensitivity has proven very important in reducing the vulnerability of the panels and for contributing to reducing the number of repairs or possible replacements brought about by damage due to shocks.